Components Description - Scotsman AF 80 Service Manual

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COMPONENTS DESCRIPTION

A. EVAPORATOR TEMPERATURE SENSOR
The evaporator sensor probe is inserted into its
tube well, which is welded on the evaporator
outlet line, it detects the temperature of the
refrigerant on the way out from the evaporator
and signals it by suppying a low voltage current
flow to the P.C. Board Micro-Processor.
According to the current received, the micro-
processor let the ice maker to continue its
operations. In case the evaporating temperatu-
re, after 10 minutes from the unit start-up, does
not go below -1°C (30°F) due to shortage of
refrigerant in the system the evaporator sensor
signal reaching the microprocessor is such to
stop immediately the unit operation, with the 5th
Warning YELLOW LED that blinks.
NOTE. The machine will remain in OFF mode
for one hour then it will restart automatically.
In case the unit trips OFF again in alarm for
3 times in 3 hours, the machine SHUTS OFF
DEFINITIVELY.
To restart the unit after the shutoff caused by
the hi evaporating temperature, it is neces-
sary to switch OFF and ON the power line
main disconnect Switch.
B. WATER LEVEL SENSOR
This sensor system consist of two small stainless
steel rods vertically fitted on the inner face of the
reservoir cover and electrically connected to the
low voltage circuit of the P.C. Board. When the
cover of the reservoir is positioned in its place the
tips of both the rods dip into the reservoir water
and detects and signals its presence by making
use of its electrical resistance.
NOTE. In the event of shortage of water in
the reservoir or, in case the water used is too
soft (de-mineralized) to cause greater
resistence to the current flow (conductivity
lower than 30 µ S) this sensor system causes
the shutoff of the machine, to protect it from
running with an interrupted or inadequate
water supply. In this situation the YELLOW
LED will glow to warn of the machine shutoff
and the reason why.
C. CONDENSER TEMPERATURE SENSOR
The condenser temperature sensor probe,
located within the condenser fins (air cooled
version) or in contact with the tube coil (water
cooled version) detects the condenser tempera-
ture variations and signals them by supplying
current, at low voltage, to the P.C. BOARD.
In case the condenser temperature sensor detects
a temperature at the condenser lower than +1
(33 ° F) that signify that the ambient temperature
is at the same value, therefore it is too low for the
correct unit operation, the sensor signals to the
microprocessor to stop immediately or to do not
start the unit operations up to the moment that
the ambient temperature will rise to more
acceptables conditions (5°C).
In the air cooled versions, in relation to the
different current received, the micro processor of
the P.C. BOARD supplies, through a TRIAC, the
power at high voltage to the fan motor so that it
can cool the condenser and reduce its temperature.
In the event the condenser temperature rises
and reaches 70
the micro processor is such to cause an imme-
diate and total stop of the machine operation.
NOTE. The machine will remain in OFF
mode for one hour then it will restart automa-
tically. In case the unit trips OFF again in
alarm for 3 times in 3 hours, the machine
SHUTS OFF DEFINITIVELY.
To restart the unit after the shutoff caused by
the hi condenser temperature, it is necessary
to switch OFF and ON the power line main
disconnect Switch.
D. GEAR MOTOR ROTATION AND SPEED
SENSOR
This safety device is housed on top of the Drive
Motor and detects - based on Hall Effect principle
- the rotating speed and rotating direction of the
drive Motor.
Should the rotating speed drop below
1300 r.p.m. the magnitude measured by this
device is such to signal to the microprocessor to
stop the unit and light-up the YELLOW LED.
About the same reaction occures when the drive
motor will tend to rotate in the wrong direction
(counterclockwise) situation that, if it occures,
will greatly affect all the freezer and gear reducer
components.
NOTE. The machine will remain in OFF
mode for one hour then it will restart automa-
tically. In case the unit trips OFF again in
alarm for 3 times in 3 hours, the machine
SHUTS OFF DEFINITIVELY. To restart the
unit after the shutoff caused by this safety
device, it is necessary first to eliminate the
cause that has generated the intervention of
the device and then switch OFF and ON the
power line main disconnect switch.
E. ICE BIN LEVEL LIGHT CONTROL
The electronic ice bin level control, located into
the ice spout, has the function to stop the operation
of the ice machine when the light beam between
the light source and the sensor gets interrupted
by the flake ice which accumulates in the spout.
When the light beam is interrupted the Bin Full
YELLOW LED located in the front of the P.C.
BOARD blinks; in case the light beam gets
interrupted for as long as 6 seconds, the ice
machine stops with the glowing-up of the 2nd
YELLOW LED to monitor the full ice bin situation.
° C
The 6 seconds of delay prevents that any
minimum interruption of the light beam due to the
regular ice chuting through the ice spout may
stop the operation of the unit.
° °
C or 60 C the current arriving to
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